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Oxidative vaporization in air using a flame with a temperature range of 1950–2300 K was employed for controlling the tip shape made from a nipper-cut metal molybdenum (Mo) wire edge. An extremely high vapor pressure of MoO3 generated on the Mo surface in flame is a driving force behind the tip shape formation. Since the MoO3 vaporization rate follows the flame temperature gradient, we could control the tip apex shape by selecting the proper flame etching condition. The best condition to obtain a sharp tip apex based on statistical tests of dozens of Mo tips was obtained by Mo wire edge insertion into the 2100 K flame from the side for one second. This was repeated twice, which reproducibly provided a tip apex with a radius of 50–100 nm and a cone angle of 20–30 degrees. The present Mo tips, fabricated without aqueous solutions, were examined for their suitability as probe tips through air-scanning tunneling microscopy (STM), ultrahigh vacuum STM, field emission spectroscopy, and conductance measurements.

Hexagonal-pillar shaped pure Fe single crystal whiskers with six {1 1 0} side planes were obtained by means of chemical vapor deposition. Atomically resolved scanning tunneling microscopy images obtained on the {1 1 0} surface showed a quasi-hexagonal atomic array with mesoscopic-range periodic height modulation of about 1/3 of an atomic step. This height modulation was found to be a result of an interference between the quasi-hexagonal top-layer and the sub-surface bcc-Fe{1 1 0} layer. Unit vectors of the mesoscopic-range modulation turned out to be expressed as p 1 → p 2 → = 13 1 - 2 14 u 1 → u 2 → = 12 1 - 3 15 s 1 → s 2 → , where u 1 → u 2 → and s 1 → s 2 → are the primitive vectors of the two-dimensional atomic array in the top-layer and those in the sub-surface layer, respectively. The two-dimensional density of atoms in the top-layer is slightly higher by 0.46% than that in the sub-surface layer.

Intermixing, growth, geometric and electronic structures of gold films grown on antiferromagnetic stacking body-centered-tetragonal manganese (0 0 1) films were studied by means of scanning tunneling microscopy/spectroscopy at room temperature in ultra-high vacuum. We found stable ordered c(2 × 2)-MnAu(0 0 1) alloy layers after depositing Au on pure Mn layers. Since at the fourth layer (5 × 23)-like Au reconstruction appears instead of the c(2 × 2) structure and local density of states peaks obtained on the c(2 × 2)-MnAu surface disappear, pure Au layers likely grow from the fourth layer.

To elucidate the magnetic properties of a magnetic multilayer film, an understanding of the local geometry, electronic structure, and possible intermixing at the interfaces is of utmost importance. By gradually increasing the Fe coverage on the Mn(001) film, we obtained this information on the interface region by means of Auger spectroscopy and scanning tunneling microscopy/spectroscopy. Intermixed atoms and various geometries and density of states are found to exist in this system.

The growth of ultrathin Mn films on an Fe(0 0 1) whisker at 370 K is studied by scanning tunneling microscopy (STM) and scanning tunneling spectroscopy at room temperature in ultrahigh vacuum. Atomically and chemically resolved STM images show that the Mn film grows with the same in-plane lattice constant as Fe(0 0 1) and that Fe atoms intermix with the first (14%), the second (4%), and the third Mn layer (2%), while a negligible amount of Fe atoms is found above the third layer. The growth mode changes from layer-by-layer to layer-plus-island at a coverage of 3 ML Mn. dI/dV curves which are normalized by voltage-dependent tunneling probability functions show clear peaks on each Mn layer. These peaks are tentatively ascribed to surface states. On the first Mn layer, peaks are found at +0.35 eV on pure Mn areas and at +0.28 eV on mixed MnFe areas. The second and the third Mn layer show peaks at +0.20 and +0.8 eV, respectively. Mn films thicker than three layers reveal besides a strong peak at +0.8 eV a weaker peak at −0.6 eV. Our apparent step height measurements show that the Mn film relaxes at the third layer: the interlayer spacing is ∼0.16 nm for the first two layers, and it increases to ∼0.18 nm at the third layer. Starting from the fourth layer the interlayer spacings are geometrically equivalent (∼0.165 nm).

The submonolayer growth of Mn on Fe(0 0 1) in the temperature range between 50 and 200 °C is studied by scanning tunneling microscopy and scanning tunneling spectroscopy. For growth temperatures above 100 °C, atomically resolved STM images with chemical contrast clearly reveal the incorporation of Mn atoms in the Fe(0 0 1) substrate. The fraction of place exchanged Mn atoms is observed to increase with growth temperature. Although on islands a c(2×2) structure forms locally which is attributed to an ordered MnFe surface alloy, long range order could not be obtained for the growth temperatures and coverages studied. Spectroscopy results are presented for clean Fe(0 0 1), pure Mn ad-islands, single incorporated Mn atoms and c(2×2)-ordered MnFe areas. In contrast to embedded Cr atoms in the Fe(0 0 1) surface [Phys. Rev. Lett. 76 (1996) 4175], isolated embedded Mn atoms do not lead to double peak structures in d I /d V curves. Nevertheless, on the ordered c(2×2) MnFe structure and the pure Mn monoatomic islands surface states are detected as peaks in the d I /d V and (d I /d V )/( I / V ) curves. However, due to the strong influence of a tip-dependent background on these peaks, the corresponding surface state energies cannot be found directly from those curves. The real surface state energies were recovered by normalizing the measured d I /d V curves by fitted quadratic backgrounds. Thus, surface state energies of about +0.35 and +0.25 eV are estimated for pure Mn islands and alloyed MnFe areas, respectively.

Various surface configurations of Cs/p-GaAs(1 1 0) have been studied by scanning tunneling microscopy and scanning tunneling spectroscopy with an interest in relation to the photoelectron emission. The local work function is found to be 4.8, 3.3, and 3.3 eV from clean p-GaAs(1 1 0), Cs one-dimensional (1D) lines (Cs coverage of 0.23 ML), and partially-ordered Cs polygons (Cs coverage of 0.5 ML), respectively. It is understood that only a coherently c(4×4)-ordered Cs-polygon surface (Cs coverage of 0.6 and 0.7 ML) can emit photoelectrons due to a sufficient reduction of the local work function down to 1.3 eV to get the negative electron affinity state. The local work function image shows that the boundary of Cs atoms has a lower local work function than at the top of Cs atoms.